-- 以下内容均基于2.1.8.RELEASE版本
紧接着上一篇[（四）SpringBoot启动过程的分析-预处理ApplicationContext] (https://www.cnblogs.com/lukama/p/14583241.html), 本文将分析上下文容器准备完成之后开始执行刷新流程
// SpringApplication.java private void refreshContext(ConfigurableApplicationContext context) { refresh(context); if (this.registerShutdownHook) { try { context.registerShutdownHook(); } catch (AccessControlException ex) { // Not allowed in some environments. } } } // 真正的refresh方法在AbstractApplicationContext类中 protected void refresh(ApplicationContext applicationContext) { Assert.isInstanceOf(AbstractApplicationContext.class, applicationContext); ((AbstractApplicationContext) applicationContext).refresh(); } // AbstractApplicationContext.java public void refresh() throws BeansException, IllegalStateException { synchronized (this.startupShutdownMonitor) { // Prepare this context for refreshing. prepareRefresh(); // Tell the subclass to refresh the internal bean factory. ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory(); // Prepare the bean factory for use in this context. prepareBeanFactory(beanFactory); try { // Allows post-processing of the bean factory in context subclasses. postProcessBeanFactory(beanFactory); // Invoke factory processors registered as beans in the context. invokeBeanFactoryPostProcessors(beanFactory); // Register bean processors that intercept bean creation. registerBeanPostProcessors(beanFactory); // Initialize message source for this context. initMessageSource(); // Initialize event multicaster for this context. initApplicationEventMulticaster(); // Initialize other special beans in specific context subclasses. onRefresh(); // Check for listener beans and register them. registerListeners(); // Instantiate all remaining (non-lazy-init) singletons. finishBeanFactoryInitialization(beanFactory); // Last step: publish corresponding event. finishRefresh(); } catch (BeansException ex) { if (logger.isWarnEnabled()) { logger.warn("Exception encountered during context initialization - " + "cancelling refresh attempt: " + ex); } // Destroy already created singletons to avoid dangling resources. destroyBeans(); // Reset 'active' flag. cancelRefresh(ex); // Propagate exception to caller. throw ex; } finally { // Reset common introspection caches in Spring's core, since we // might not ever need metadata for singleton beans anymore... resetCommonCaches(); } } }在refresh方法中清晰的划分了刷新容器的步骤。
prepareRefresh()主要用于清除元数据Reader的缓存，设置应用程序启动的时间，设置应用程序的活动标记，初始化属性源。
// AnnotationConfigServletWebServerApplicationContext.java protected void prepareRefresh() { this.scanner.clearCache(); super.prepareRefresh(); } // AbstractApplicationContext.java protected void prepareRefresh() { // 设置开始执行的时间和活动标记 this.startupDate = System.currentTimeMillis(); this.closed.set(false); this.active.set(true); if (logger.isDebugEnabled()) { if (logger.isTraceEnabled()) { logger.trace("Refreshing " + this); } else { logger.debug("Refreshing " + getDisplayName()); } } // ① initPropertySources(); // ② // Validate that all properties marked as required are resolvable: // see ConfigurablePropertyResolver#setRequiredProperties getEnvironment().validateRequiredProperties(); // ③ // Store pre-refresh ApplicationListeners... if (this.earlyApplicationListeners == null) { this.earlyApplicationListeners = new LinkedHashSet<>(this.applicationListeners); } else { // Reset local application listeners to pre-refresh state. this.applicationListeners.clear(); this.applicationListeners.addAll(this.earlyApplicationListeners); } // Allow for the collection of early ApplicationEvents, // to be published once the multicaster is available... this.earlyApplicationEvents = new LinkedHashSet<>(); }① - 初始化属性资源
// StandardServletEnvironment.java public void initPropertySources(@Nullable ServletContext servletContext, @Nullable ServletConfig servletConfig) { WebApplicationContextUtils.initServletPropertySources(getPropertySources(), servletContext, servletConfig); } // WebApplicationContextUtils.java public static void initServletPropertySources(MutablePropertySources sources, @Nullable ServletContext servletContext, @Nullable ServletConfig servletConfig) { Assert.notNull(sources, "'propertySources' must not be null"); String name = StandardServletEnvironment.SERVLET_CONTEXT_PROPERTY_SOURCE_NAME; // servletContext不为空且有相关配置的情况 if (servletContext != null && sources.contains(name) && sources.get(name) instanceof StubPropertySource) { sources.replace(name, new ServletContextPropertySource(name, servletContext)); } // servletConfig不为空且有相关配置的情况 name = StandardServletEnvironment.SERVLET_CONFIG_PROPERTY_SOURCE_NAME; if (servletConfig != null && sources.contains(name) && sources.get(name) instanceof StubPropertySource) { sources.replace(name, new ServletConfigPropertySource(name, servletConfig)); } }